15-Pentadecanolide (oxacyclohexadecan-2-one) is a valuable musk odorant which occurs in angelica root oil (K. Bauer, A. Garbe, Common Fragrance and Flavor Materials, p. 104, VCH, Weinheim, 1985).
It is known to prepare 15-pentadecanolide by hydrogenating the double bond of 15-pentadecenolide. 
15-Pentadecenolide can be prepared according to Russian Chemical Bulletin, 47, 6, 1998, 1166 and is usually in the form of a mixture of 15-pentadecen-11-olide and 15-pentadecen-12-olide. This double bond isomer mixture is referred to in the present case as 15-pentadecen-11(12)-olide.
In JP 01090182 A2 (Chemical Abstract Number 1989 : 534017), the catalyst used is Raney nickel for hydrogenating 15-pentadecen-11(12)-olide in ethanolic solution.
Russian Chemical Bulletin, 47, 6, 1998, 1166 describes palladium catalysts for the hydrogenation. 15-Pentadecen-11(12)-olide is hydrogenated with palladium on activated carbon or palladium on aluminum oxide to give 15-pentadecanolide, optionally with the addition of a base such as sodium carbonate.
The processes for the preparation of 15-pentadecanolide from 15-pentadecen-11(12)-olide mentioned exhibit serious disadvantages in cases of industrial production. In addition to the high hydrogen pressures and any additions of base, the dilution with solvents and the high use amount of catalyst are particularly disadvantageous. In the case of Raney nickel, the pyrophoric, toxic and allergenic properties of the catalyst are particularly disadvantageous.
In general, the 15-pentadecanolide originating from these hydrogenations has following the thermal stress of a distillation, a scorched note in terms of odor, which often requires further purification in order to obtain a perfumistically acceptable quality.
There is also the need to find a process which produces 15-pentadecanolide in an economic manner, in a high yield and of a good perfumistic quality.